Re: [PATCH 3/3 v12] printk: Add monotonic, boottime, and realtime timestamps

[Petr Mladek <pmladek@suse.com>]

On Mon 2017-09-18 13:51:00, Prarit Bhargava wrote:
> printk.time=1/CONFIG_PRINTK_TIME=1 adds a unmodified local hardware clock
> timestamp to printk messages.  The local hardware clock loses time each
> day making it difficult to determine exactly when an issue has occurred in
> the kernel log, and making it difficult to determine how kernel and
> hardware issues relate to each other in real time.
> 
> Make printk output different timestamps by adding options for no
> timestamp, the local hardware clock, the monotonic clock, the boottime
> clock, and the real clock.  Allow a user to pick one of the clocks by
> using the printk.time kernel parameter.  Output the type of clock in
> /sys/module/printk/parameters/time so userspace programs can interpret the
> timestamp.
> 
> diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
> index 512f7c2baedd..5e0bf2ef02f7 100644
> --- a/kernel/printk/printk.c
> +++ b/kernel/printk/printk.c
> @@ -1201,14 +1204,130 @@ static inline void boot_delay_msec(int level)
> +static int printk_time = CONFIG_PRINTK_TIME_TYPE;
> +
> +static int printk_set_ts_source(enum timestamp_sources ts_source)
> +{
> +	int err = 0;


> @@ -1861,6 +1980,7 @@ static size_t msg_print_text(const struct printk_log *msg,
>  			     bool syslog, char *buf, size_t size) { return 0; }
>  static bool suppress_message_printing(int level) { return false; }
>  
> +static int printk_time;

I worried if the variable should have got initialized. But it seems to
be a relic from an older version. The variable is not longer used and
needed when CONFIG_PRINTK is not defined. It is proved by gcc:

  CC      kernel/printk/printk.o
kernel/printk/printk.c:1983:12: warning: ‘printk_time’ defined but not used [-Wunused-variable]
 static int printk_time;


>  #endif /* CONFIG_PRINTK */
>  
>  #ifdef CONFIG_EARLY_PRINTK

Otherwise that patch looks fine. With the unused variable removed,
feel free to use:

Reviewed-by: Petr Mladek <pmladek@suse.com>

Best Regards,
Petr